Lighting in the aquarium is not just a tool that allows us to observe our aquarium and the inhabitants, it is also required to aid plant growth with photosynthesis and some species of fish prefer bright lighting to be at their best. Many species of fish prefer subdued lighting so this is why there is such a large choice of lighting available to us.
Some of the most common systems include the following tubes
Actinic/White tubes- these are commonly used in marine aquariums as they emit a strong white light as well as light from the blue range of the spectrum which is very important for the corals in the aquarium. They tend to give a nice hue in the tank making it perfect for viewing as well.
Day-Glo tubes- these provide light from the full spectrum thus replicating sunlight hitting the water, you will often see these used in a general tank set up or a community tank.
Color-Glo tubes- When you are after a softer light, these tubes are ideal, they emit a soft glow by using colors from the other end of the spectrum, namely yellows and reds. They are ideal for fish that do not like bright lighting and the tank looks cozy when using these.
Plant-Grow tubes- These are specially designed for planted aquariums and emit light from the red and blue color spectrum. Photosynthesis is enhanced with this lighting thus producing better growth and foliage color from the plants.
High Intensity tubes- These are really powerful and are used to penetrate the deeper reef aquariums so that the bottom dwellers do not miss out on the light source. They have a high Kelvin rating, often up to 20,000K and emit a white/blue light.
As mentioned above there are now choices which type of lighting system we can use, Metal Halides are now very popular with the reef aquarist, they emit a high lighting level but they do use a lot of power to keep the aquarium illuminated.
LED systems are also entering into this hobby and are a lot cheaper to run that all of the other systems, there is a drawback though, they are still very costly to purchase from new. This system does not use tubes but has rows of LED bulbs that perform the same function.
When selecting your lighting always check the amount of lighting that is required to illuminate the water volume in your tank and never use less than is advised, remember that this can be affected by the depth of the tank as well. Always use timers to run your lighting system and never leave the lighting on for too long as this can also encourage algal growth in the aquarium.